The Organ Pipes National Park is situated off the Calder Freeway, almost opposite the Speedway and contains one of Melbourne's premier natural attractions. The Friends group was formed in 1972, and boasts the oldest Friends group in Australia. The Friends have helped transform what was then totally degraded farmland to re-establish an area of indigenous vegetation. Since 1997, the Friends have been working on "Costa's block" in the south of the Park. Many volunteers and thousands of hours have been spent removing old car bodies, thistles, prickly pear etc. Along the creek a solid wall of boxthorn, willows and blackberry have hindered the Friends' activity, but access for machinery to the creek via tracks is relatively easy. With funding from Melbourne Water and Parks Victoria, the Friends group has employed contractors to remove some boxthorn from an area above the creek. The Friends have also undertaken poisoning of willows and removal of boxthorn along the creek. Much weeding and replanting have been done near the Calder Highway above the riparian zone. There are also active research projects on local bats and sugar gliders.